Thread tensioning apparatus



' Nov.,18, l96 9 P. C.EPPEN'DAHL ET AL 3,478,983

THREAD TENSIONING APPARATUS Filed March 16, 1966 2 Shets-Sheet 1INVENTORS PEEREE C. EPPENDAHL Loan-Jpn, 23M w W541 A'rrorme NOV- 18,1969 p, c, EPPENDAHL ET AL 3,478,983

THREAD TENSIONING APPARATUS Fild March 16, 1966 v 2 Sheets-Sheet zINVENTORS PIERRE C. EPPENDAHL Q a/M BY MJ, 8M wax ATTORNEY} UnitedStates Patent 3,478,983 THREAD TENSIONING APPARATUS Pierre CharlesEppendahl, Lyon, and Pierre Maurin, Caluire, France, assignors toThermiguides S.A., Lyon, France, a company of France Filed Mar. 16,1966, Ser. No. 534,729 Claims priority, application France, May 14,1965,

45,988 Int. 01. B6511 59/12 US. (:1. 242 -1s4 8 Claims ABSTRACT OF THEDISCLOSURE Thread tension control mechanism in which a tension applyingdevice is actuated by tension'sensitive means on which the thread actsin opposition to pressure in a pneumatic system and wherein the pressurein the pneumatic system is maintained by a movable part subject to suchpressure and having applied to it a determined but adjustable force tomaintain such pressure.

Thisinvention relates to thread tension control mechanism for textilemachinery and has for an object to provide a simple form of apparatuswhich will allow for the effective control of one or more threadtensioning mechanisms from a control station so that, where there aretwo or more tension control mechanisms controlled from the controlstation, the tension maintained by the control mechanisms can besimultaneously and similarly controlled and maintained.

(l) A tension-sensitive device, usually in the form of aflever with athread guiding eyelet at one end and secured at its other end to apivoted spindle to which is applied a predetermined torque in adirection opposite to that applied to it by the tension in the'thread sothat the lever at any moment takes up a position determined jointly bythe torque applied to the spindle and the tension of the thread at thatmoment.

(2) A tensioning device comprising one of the well known types of threadbrake, e.g. a pair of discs pressed towards one another by a variableforce so as to compress the thread between their flat faces, or acylindrical body around which the thread passes having associated withit means by which the are over which the. thread is held in contact withit can be varied, or a comb type tensioning device comprising tooth-likeprongs giving to a part of the thread a zigzag path and movable so as tovary'the degree to which the prongs intermesh and therefore the form ofthe zigzag path.

(3) A mechanical connection between the tension-sensitive device and thetensioningdevice whereby the tension-sensitive device, which is disposedso as to be sensitive to the tension maintained in the thread by thetensioning device, operates on the tensioning device to increase thetension if the tension-sensitive device moves in a direction indicatinga reduction in tension and to decrease the tension if thetension-sensitive device moves in a direction indicating an increase intension.

It is important that the tension-sensitive device, which in most casesis a lever as mentioned above, should be as light as possible so that itwill react with substantially no delay to any change in the tension inthe thread,and

3,478,983 Patented Nov. 18, 1969 not lag appreciably behind itstheoretically correct position at any instant due to inertia effects.

In the employment of such thread tensioning apparatus it would be ofconsiderable advantage in types of winding or spinning machine embodyinglarge numbers of spinning twisting or winding units (often as many as200 such units) all driven together, if the output tension of all thetension control devices could be controlled from a single controlstation, thus reducing very greatly the time needed to set the wholemachine to operate at the required ten- SlOIl.

Where simple tensioning apparatus is used which only applies a fixedamount of frictional drag to the running strand of thread irrespectiveof the tension at which the thread enters the tensioning device, varioussystems have been proposed, including electrical, mechanical, pneumaticand hydraulic systems, which vary the force applied to the movable discof a tensioning device comprising movable and fixed discs between whichthe thread is gripped. For example, in some cases the tension may be setby applying a predetermined electro-magnetic force to the movable discof such a device while in other cases the thread passes between thesurface of a rigid member and the surface of a flexible metal sheetacted upon by a column of air so as to press the sheet towards the rigidmember, and it will be seen that with such devices by varying theelectromagnetic force or the pressure of the column of air in a numberof similar devices the frictional drag applied by a number of devices tothe threads on which they act can be controlled simultaneously.

When, however, it is desired to control a number of tension-controldevices each constructed to provide compensation for variations in thetension of the thread entering the device, the problem is morecomplicated since it is not a case merely of controlling the pressureapplied to a length of thread passing between the surfaces of twoplates, which pressure, once set, is not varied, but is a question ofvarying the braking effect applied to the thread in accordance withmovement of a tension-sensi tive lever or like tension-sensitive deviceon which the thread acts in one direction and a predetermined force actsin opposition to the force applied to it by the thread, the brakingeffect thus being varied automatically in accordance with the tension inthe thread entering the control device so as to maintain a constanttension in the thread leaving the control device. What is needed,therefore, is a system in which the predetermined force opposing that ofthe thread can be applied to any desired number of tension sensitivelevers or like tension-sensitive devices simultaneously, and can beprecisely varied at any time from a single control position.

For this purpose the use of a stream of air acting on a vane type motorhas been proposed, as has the use of a diaphragm on which a column ofcompressed air derived from a source of compressed air acts inconjunction with gearing arranged to convert the displacement of thecentre of the diaphragm into torque applied to the spindle on which thetension-sensitive lever and eye are mounted. These systems are subjectto the various disadvantages of systems which demand complicated andoften ineffective filtration equipment in order to avoid theaccumulation of liquid within the column of air which reducessensitivity or even renders the apparatus inoperative. Moreover in suchsystems employing a column of air under pressure, while means 'areprovided which automatically admit additional air to restore the saidpres sure following a drop in pressure there are no means permittingescape of air to prevent a rise in pressure above the said pressure. Thesystems in question do not, therefore, take into account the effect ofsimultaneous similar movements of the tension-sensitive levers of anumber of the devices which will reduce the total volume of air in thesystem and thus cause a rise in the pressure in the column and hencemal-operation of neighbouring devices. Pressures substantially above theset pressure may therefore be created and exist in the system for longperiods. Such systems also require the use of a compressed air supplyinvolving the cost of installing and maintaining such supply, evendisregarding the power needed for this purpose.

It is an object of the present invention to provide a form of threadtension control apparatus which will not be subject to the disadvantagesindicated above as present in existing systems, which will be simple andwill, when required, enable a large number of tension control devices tobe simultaneously and similarly controlled from a single control pointand will not involve the expenditure of power.

Thread tension control mechanism according to the present inventioncomprises a movable tension-sensitive member arranged to be acted uponby the thread so that increases in the tension of the latter causemovement of such tension-sensitive member against the action of acontrolling force and vice versa, and a tension applying device actuatedby such movement of the tension-sensitive member in a manner tending tomaintain a constant tension in the thread for any given value of thecontrolling force, 'wherein the means for applying the controlling forcecomprises a pneumatic system the pressure in which is at any moment thesame throughout the system and can be adjusted by an adjustable pressurecontrolling device which includes at least one movable part which issubject to the pressure in the system and is arranged to have adetermined but adjustable force applied to it to determine the pressuremaintained in the system.

Since the movable part therefor has a constant force applied to it, itmaintains automatically a constant pressure in the system and thereforea constant precise force acting on the tension-sensitive levers or othertension-sensitive devices, any movement of one or more of thetension-sensitive levers or like-tension-sensitive devices in no wayaffecting the pressure in the system since any change in the volume ofair in the system will merely result in a movement of the movable wallwithout a change in the force applied to it. It will be understood thatthere may be momentary increases or reductions in the pressure in thesystem which causes movements of the movable wall but such changes willbe both momentary and slight, assuming, as will be the case, that themovable wall has small or negligible inertia.

Conveniently the pressure controlling device is in the form of a chamberone wall at least of which is movable to vary the capacity of thechamber, and means for applying to that wall the determined butadjustable force whereby any one of a number of corresponding determinedpressures within a predetermined pressure range can be maintained withinthe whole system, independently of limited changes which may occur inthe volumetric capacity of the system as a whole. For example, the forceapplied to the movable wall may be applied by means of a weight orweights so that, by selection of the appropriate weight or weights anydesired pressure within the predetermined pressure range can bemaintained throughout the system.

In any case it will be seen that the fluid in the pneumatic system actsmerely as a transmission element between the means for applying therequired force to the tension-sensitive members and the movable wall towhich a constant but adjustable force is applied by a weight or othermeans.

The chamber may be in the form of a cylinder and piston assembly ofwhich the piston constitutes the movable wall or for example in the formof a bellows device one end of which constitutes the movable wall. Inany case the force applied to the movable wall, whether by weights orotherwise, may be applied in a direction such as either to maintain apressure in the system above atmospheric pressure or to maintain apressure in the system below atmospheric pressure, preferably thelatter.

Preferably the tension-sensitive device will be in the form of an armwhich is connected at one end to a spindle mounted to rock in bearingsand carries at its other end an eye through which the thread passes inits travel between two fixed guides disposed so that the tension in thethread tends to rock the arm and its spindle about its pivotal axis inone direction, while the spindle is urged in the other direction by apneumatic device, e.g. in the form of a diaphragm, which is subject tothe air pressure in the pneumatic system and thus applies to the spindlea force dependent upon the pressure in the pneumatic system. Themovement of the arm then serving to vary the braking force applied tothe thread by a braking device in advance of the tension-sensitivedevice. In one such arrangement employing a pneumatic diaphragm subjectto sub-atmospheric pressure in the system the centre of the diaphragmmay be connected to one end of a short length of high tensile syntheticyarn the other end portion of which is wound around the spindle, or apulley on the spindle, two or three times so that when a subatmosphericpressure is applied to the face of the diaphragm remote from the hightensile synthetic yarn, the diaphragm exerts a tension on the length ofyarn tending to rotate the spindle. Such a device will thus be sensitivewith very little inertia and be substantially frictionfree as comparedwith arrangements embodying, for example, rack and pinion gearing.Moreover the use of subatmospheric pressure in the pneumatic systemreduces the specific mass of air present in the system, thus reducinginertia effects, the sensitivity of the system being in fact inverselyproportional to the inertia of the various parts and masses which haveto move to control the tension.

In addition the employment of sub-atmospheric pressure avoids any needfor scavenging or filtering units or bleed units for removing moisture.In machines embodying a tension control mechanism according to theinvention employing a number of tension control devices the column ofair the pressure of which determines the tension to be maintained can beled to the various units by way of the hollow tube which in many casesruns the length of the machine and has the tension regulating devicessupported upon it.

One form of apparatus according to the invention and a modificationthereof are shown in the accompanying drawings, in which:

FIGURE 1 is a diagrammatic view of a complete control system asinstalled,

FIGURE 2 is a front elevation of one of the tension controlling units,

FIGURE 3 is a cross sectional side elevation on the line 3-3 of FIGURE2,

FIGURE 4 is a cross section on the line 4--4 of FIG- URE 3,

FIGURE 5 is a front elevation on a somewhat larger scale than FIGURES 2and 3 of the frictional device by which the tension is controlled,

FIGURE 6 is a plan view of the device shown in FIGURE 5,

FIGURE 7 is a sectional side elevation of a modification of thearrangement shown in FIGURE 1, and

FIGURE 8 is a side elevation showing a modification of the arrangementshown in FIGURE 4.

In the arrangement shown in FIGURE 1 the control system comprises a unitA for providing a controlled subatmospheric pressure in a pneumaticsystem comprising a passage B representing a pneumatic column, whichpassage is connected by branch passages C to the individual tensionregulating units p p pg, 17 17, which may be any convenient number asindicated, and by a further passage to a sub-atmospheric pressurereservoir D. As shown in FIGURES 2, 3 and 4 each of the tensionregulating units 17 p etc. comprises two half shells 1a and 1b betweenflanges on which is gripped in a fluid tight manner the edge of adiaphragm 2, constituting a pressure Sensitive member, which thusprovides an air tight partition between a chamber subject tosub-atmospheric pressure due to its connection with the passage C and achamber which is subject to atmospheric pressure. The half shell 1asupports a casting 4 constituting a supporting member in which ispivotally mounted, preferably upon ball bearings 5, a spindle 6 whichhas rigidly attached to it a pulley 7 and one end of a lever 8,constituting the movable tension sensitive means, the lever beingprovided at its other end with a thread guide 9. A small friction pad 10may be provided around the spindle 6, if needed, to prevent the threadcutting into the spindle 6.

Some small amount of frictional damping may be applied to the spindle 6in some cases.

The diaphragm 2 is connected at its centre by a connecting piece 11 toone end of a thin and flexible length of yarn or cable 12 constituting atension member the opposite end portion of which is wound round thecircumferential surface of a pulley 7 on the spindle 6 and is anchoredto a predetermined point on the rim of the pulley.

Also carried by the supporting piece 4 is a plate 13 provided with twofixed thread guides, as indicated generally at 14 and 15, which serve toguide the thread respectively on its way to and from the tensionregulating unit. In some cases the guide 15 may be unnecessary, that isto say where the disposition of the parts is appropriate.

Also rigidly secured to the plate 13 is the stationary part 16 of atension applying device, this part being of arcuate form and U-shapecross section as shown in FIGURES 2 and 3 and having in its upturnedlateral edges notches 17 which serve to guide the thread in its passageacross the part 16, while the other part of the thread tensioning devicecomprises an arcuate shaped rib 18 secured to a plate 8a rigid with thearm 8 and lying and moving between the upturned sides of the part 16,the rib 18 varying in depth throughout its length so that the degree ofdeflection imposed by its on the part of the thread extending across thepart 16 between the notches 17 depends upon the angular position of thearm 8.

The sub-atmospheric pressure which exists in column B, C causes thediaphragm 2 to be forced by atmospheric pressure to the right in FIGURE4 and this in turn applies tension to the thread 12 which imparts to thespindle 6 and lever 8 a torque tending to deflect the lever 8 in thedirection shown by the arrow x in FIGURE 2 thus causing the guide 9 tobear against the part of the strand of thread 19 between the frictionaldevice 16, 18 and the guide 15 as shown. If, therefore, the tension inthe thread approaching the guide 14 should decrease so that the tensionin the part of the thread between the device 16, 18 and the guide 15similarly decreases the lever 8 will move to the left in FIGURE 2 sothat the rib 18 moves arcuately within the U-shaped member 16 to depressthe part of the thread extending across the U- shaped member 16 moredeeply into the space between the notches 17, thus increasing thetension of the thread by the application of increased friction theretoto a degree depending upon the tension of the thread approaching theguide 14. Thus each tension controlled device acts in a manner tendingto maintain substantially constant tension in the part of the threadleaving its guide 15.

The adjustable pressure controlling device shown in FIGURE 1 forapplying and maintaining the desired subatmospheric pressure in thecolumn B, C comprises a cylinder 21 the upper end of which is in directcommunication with the passages B, C, the cylinder 21 containing amovable part constituted by a piston 22 provided with a piston rod 23extending below the lower end of the cylinder 21 and provided at itslower end with a supporting platform 24 on which weights 25 can beplaced. A

valve'26 is provided which when opened allows the piston 22 to be raisedto the top of its cylinder 21 while it can also allow the system to bemomentarily connected to a reduced pressure source during operation ifdesired. In any event the valve 25 is closed during normal operation ofthe system with the piston 22 in an appropriate position near the top ofthe cylinder 21 and a suitable load applied by the weights 25 to thepiston.

It will thus be seen that by the selection of suitable weights forapplication to the platform 24 any desired sub-atmospheric pressurewithin an appropriate range can be applied to and maintained in thesystem comprising the passages B, C and that this selectedsubatmospheric pressure will be maintained independently of movements ofthe diaphragms 2 and of changes in temperature.

If desired, instead of the piston and cylinder arrangement shown at 21,22, 23 in FIGURE 1, a bellows arrangement as shown in FIGURE 7 may beemployed comprising a bellows 27 the interior of which is in continuouscommunication with the passage C and has associated with it a valve 26corresponding to the valve 26 in FIGURE 1, the lower end of the bellowshaving secured to it the upper end of a rod 23' the lower end of whichcarries a supporting platform 24 on which weights 25 can be placed sothat the device as a whole maintains a sub-atmospheric pressure in thepassages B, C in a similar manner to the device 21, 22, 23, 24, 25 inFIGURE 1. In the construction shown in FIGURE 7 the bellows hasincorporated in it a hydraulic damping device of the dashpot typeindicated at 28 to prevent vertical vibratory movements of the lower endof the bellows.

In the modification shown in FIGURE 8, which may be regarded asincorporated in the part of the apparatus shown in FIGURE 4, instead ofthe corresponding parts shown in FIGURE 4, the spindle 6 has rigidlymounted on it two adjacent pulleys 29 and 30 of different effectivediameter while the diaphragm 2 has a pulley 31 mounted in bearings 32for example ball bearings, in a bracket attached to the centre of thediaphragm, the tension thread 12 passing around the pulley 31 and beingsecured at its ends respectively to the circumferential parts of thepulleys 29 and 30 at diametrically opposite points. This arrangementprovides differential apparatus by which measurable differences in thesub-atmospheric pressure acting on the diaphragm 2 will produce verysmall differences in torque on the spindle 6 and lever 5.

It is to be understood that the invention also includes within its scopesystems similar to those described as employing sub-atmosphericpressures but in which, instead of a piston and cylinder device or abellows and weights producing a sub-atmospheric pressure, a piston andcylinder or bellows assembly and weights are arranged to provide asuper-atmospheric pressure in the pneumatic system, it being understoodthat in this case the mechanism connecting the diaphragms or the like tothe tension control members would be correspondingly modified so thatthe torque applied to the spindle 6 or its equivalent due to thesuper-atmospheric pressure would be in the correct direction.

What we claim as our invention and desire to secure by Letters Patentis:

1. Thread tension control mechanism comprising:

movable tension-sensitive means arranged to be acted upon by a thread sothat increases in the tension of the latter cause movement of said atleast one tension-sensitive means against the action of a controllingforce and vice versa;

a tension-applying device actuated by such movement of said at least onetension-sensitive means in a manner tending to maintain a constanttension in the thread for any given value of the controlling force;

means for applying the controlling force comprising a pneumatic systemcontaining fluid the pressure of which is at any moment the samethroughout the system, a pressure sensitive member subject to thepressure of the fluid in the pneumatic system, and an adjustablepressure-controlling device for adjusting the pressure in the system,said adjustable pressure controlling device including at least onemovable part which is subject to the pressure in the system; and

means for applying a determined but adjustable force to said movablepart to maintain a corresponding determined but adjustable pressure inthe system.

2. Thread tension control mechanism as claimed in claim 1 in which thepressure controlling device is in the form of a chamber forming part ofthe pneumatic system and one wall at least of which is movable to varythe capacity of the chamber and constitutes the movable part on whichthe means for applying the adjustable force acts.

3. Thread tension control mechanism as claimed in claim 2 in which saidtension-sensitive means comprises a pivoted spindle having acircumferential surface thereon, an arm one end of which is rigidlyconnected to said spindle, a thread guide at the other end of said arm,said pressured sensitive member comprising a diaphragm, and a tensionthread having one end portion wound at least partially around the saidcircumferential surface on the spindle and connected at its other end tosaid diaphragm.

4. Thread tension control mechanism as claimed in claim 3 in which themeans for applying said adjustable force to said movable wall comprisesa support attached to said movable wall and arranged to have weights ofvarious mass applied to it.

5. Thread tension control mechanism as claimed in claim 2 in which themeans for applying said adjustable force to movable wall comprises asupport attached to said movable wall and arranged to have weights ofvarious mass applied to it, and wherein the means for applying theadjustable force to the movable wall applies such forces in a directionto increase the volumetric capacity of the chamber so as to providetherein and in the pneumatic system a sub-atmospheric pressure.

6. Thread tension control mechanism as claimed in claim 1 in which saidtension-sensitive means comprises a pivoted spindle, an arm one end ofwhich is rigidly connected to said spindle, having a circumferentialsurface thereon a thread guide at the other end of said arm, saidpressure sensitive member comprising a diaphragm, and a tension threadhaving one end portion wound at least partially around the saidcircumferential surface on said spindle and connected at its other endto said diaphragm. 7. Thread tension control mechanism as claimed inclaim 1 including a plurality of tension-sensitive means and associatedtension-applying devices each actuated by movement of its associatedtension-sensitive means, wherein the pneumatic system comprises a tubeserving not only to' transmit the adjustable pneumatic pressure to eachpressure sensitive means but also as a support for eachtension-sensitive means and their associated tensionapplying devices.

8. Thread tension control mechanism as claimed in claim 1 in which saidat least one movable tension-sensitive means comprises a pivotedspindle, an arm one end of which is rigidly connected to the spindle, athread guide at the other end of said arm, in which said pressuresensitive member comprising a diaphragm, two pulleys of differentdiameter secured to said spindle, a third pulley rotatably connected tosaid diaphragm and a flexible tension thread the ends of which areconnected respectively to circumferential points on said two pulleyswhile an intermediate part thereof passes round said third pulley.

References Cited UNITED STATES PATENTS 2,610,813 9/1952 Campbell 242-2,888,216 5/1959 Simons, et al. 242149 X 3,223,351 12/1965 Lemarchand242154 STANLEY N. GILREATH, Primary Examiner

